Test tube heater



Nov. 13, 1956 A. G. JORDAN TEST TUBE HEATER Filed Feb. 18. 1954 1 JNVENTOR. AWTl/O/VY a. Jqem/v BY Z HIS ATTOFMSYS United States Patent TEST TUBE HEATER Anthony G. Jordan, Battle Creek, Mich.

Application February 18, 1954, Serial No. 411,073

Claims. (Cl. 219-43) This invention relates to test tube heaters and more particularly to a device simplifying handling of test tubes during chemical analyses.

In the usual operation a test tube is held by hand over a Bunsen burner. In the application of heat to a test tube by means of a Bunsen burner violent boiling and bumping often occurs. In many operations specimens or reagents are added to the contents of the test tube during heating. These and other necessary operations have to be done with the one remaining free hand.

In other general laboratory and research tests, such as the testing of urine for sugar and for albumin, there may be two or more determinations involved which are extremely difiicult to effect at one time.

One of the objects of the present invention is the provision of means whereby two or more tubes can be heated simultaneously and without manual handling.

A further object of the invention is a device which provides application of heat to the tube, anywhere along its length, by an adjustableheating element which partially surrounds the tube so that heat is applied to the contents of the tube, or at the top if desired, and violent ebullition and bumping are to be generally reduced if not entirely eliminated.

A further object of the invention is the provision of a readily replaceable heating unit.

A further object of the invention is the provision of an improved rack for holding test tubes which aifords also a heating unit.

Other objects and advantages reside in the construction of parts, the combination thereof and the mode of operation, as will become more apparent from the following description.

Referring to the drawings,

Figure 1 is a perspective view of the test tube heater.

Figure 2 is a vertical cross section taken substantially on the line 22 of Figure 1, but showing the whole of the heating unit in elevation.

Figure 3 is a horizontal sectional view taken on the line 3-3 of Figure 2.

Figure 4 is a detail vertical sectional view taken on the line 44 of Figure 3.

Referring in detail to the drawings, a rack or main frame is formed of vitreous, fire resistant non-conductive material, and capable of withstanding wide ranges of temperature. The rack 10 has a base portion 12, provided with one or more depressed areas 14 for receiving and supporting a test tube. The rack may be curved over, as shown in the drawings, or right angularly formed or assumes any desired configuration which provides an overhanging ledge 16. Any configuration desired may be used, so long as an upper portion is present to provide an upper support for the test tube. A plurality of substantially semi-circular recesses 18 is provided in the edge of the ledge portion 16 in such relation to the depressions 14 that a test tube, as shown at 20 in dotted lines in Figures 1 and 2, can rest in the depression and, standing at a slight angle, be received in and be Patented Nov. 13, 1956 supported by the recess 18. The body of the rack 10 has a recess or hollow portion 22, the rear wall 24 of which is provided with an aperture, not shown as such, which receives the insulated lead-in electric cord 26.

The side wall 28 of the recess 22 is provided with the electric switch 30. The lead-in cord 26 is led through the rear wall 24 of the rack, as shown at 27, and is divided (division not shown) within the recess 22, of the rack 10. An opening 23 in an intermediate wall 25 of the rack 10 is of such formation as to receive the insulating sheath 32 of a pair of conductors 38 and 40.

A heating unit 42 comprises two non-conducting ceramic body portions 44 and 46 which have complementary projection 47 and recess 48 respectively for nonsliding engagement. The portion 44 must be of fire resistant material, since it carries the heating element later described. The body member 46 is molded with an inset opening to receive the end of the sheath 32. It is also provided with a pair of laterally extending ducts which receive the ends of conductors 38 and 40. Cylindrical openings 50 and 52 in the body portion 44 coincide with pockets 54 and 56 in the body portion 46 to receive the conductors or conducting rods 58 and 60. The pockets 54 and 56 are lined with copper conductors or sleeves 62 and 64. The ends of the conductors 38 and 40 contact the sleeves 62 and 64 respectively.

The heating unit 42 is tiltable by flexing the insulating sheath and the conductors 38 and 40 therein. This allows the heating element later described to fit the test tube closely.

The body portion 44 has a semi-circular formation at its outer side, of such form and size as to receive a test tube as the tube rests in the depression 14 and the recess 18 as above described. The body portions 44 and 46 are provided with an upper flange 66 and a lower flange 68 which are part of the body portions and form a recess 70. A metal or other spring band 72 of substantially rectangular C-shape snaps into this recess 70 to hold the blocks 44 and 46 together. The end portions 74 and 76 snap over the front short areas 78 and 80 of the body portion 44.

The conducting rods 58 and 60 make contact with the ends of a heating element 82 through conducting members 83. The seat 84 has a semi-circular or C- shaped formation which will fit around a test tube. The heating element 82 is secured by a poured cement 85.

A series of spaced projections 86 bridge the tube from actual contact with the heating element. Being spaced from one another they are prevented from causing a concentration of their own heat in a ring around the tube.

fingers on the ends 74 and 76 of the spring band mem-.

ber, pressing them outward until they are free from their clamping engagement over the ends of the part 44.

The two heating elements 82 may be connected in series with each other, in series with the switch 30, and in series with the cord 26. In order to heat the test tubes, it is merely necessary to place them upon the rack as shown, plug the cord 26 into a suitable outlet, and actuate the switch 30. When the contents in the tubes have reached the desired temperature and the test is completed, the switch 30 may be turned off and the tubes allowed to stand in the rack to cool, if this is desirable. The heating elements may be replaced by removing the old heating element, as described above.

The testing apparatus is convenient to use and may be easily stored. When in use, it is not necessary for the technician to hold the test tubes while being heated, in that they may be placed in position and left in this position until the desired test results have been obtained.

Although the preferred embodiment of the device has been described, it will be understood that within the purview of this invention various changes may be made in the form, details, proportion and arrangement of parts the combination thereof and mode of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and defined in the appended claims.

Having thus described my invention, I claim:

1. In laboratory apparatus for heating test tubes, a ceramic body, a lead attached to said body, a heating unit comprising a fixed portion and a replaceable portion, said replaceable portion having a C-shaped front surface portion for receiving tubes, and a heating element disposed upon and glued to said front surface, cylindrical openings in said replaceable portion, conductors disposed in said openings and connecting with said heating element, said conductors protruding from the rear of said replaceable element, cylindrical openings disposed in said fixed portion aligned with the first mentioned cylindrical openings, copper sleeves in said last mentioned cylindrical openings adapted to receive and continue contact with said protruding conductors, a pair of additional cylindrical openings disposed at right angles to the before mentioned cylindrical openings, conductors received in said openings and contacting said copper sleeves, said conductors continuing contact from said copper sleeve to said lead.

2. In laboratory apparatus a heating unit tilted at an angle to the horizontal and comprising a replaceable portion and a portion fixed to a lead, said fixed portion provided with a pair of cylindrical openings for receiving conductors from said leads, a pair of cylindrical openings in said replaceable portion aligning with the openings in said fixed portion, a C-shaped surface positioned at the front of said detachable portion, a heating element disposed on said C-shaped surface, projections intermittently positioned on said C-shaped surface and formed integrally therewith, conducting rods connected to the ends of said heating element and extending through and protruding from said openings in said replaceable element and into the aligned openings in said fixed portion, copper sleeves in the openings in said fixed portion, a pair of additional cylindrical openings in said fixed portion disposed substantially at right angles to said first mentioned openings, and terminating therein at one end, conductors disposed within said last mentioned openings and making contact between said copper sleeve and said lead.

3. In laboratory apparatus a heating unit tilted at an angle to the horizontal and comprising a detachable portion and a portion fixed to a lead, said fixed portion provided with a pair of cylindrical openings for receiving conductors from said leads, a pair of cylindrical openings aligning with the openings in said fixed portion, a C- shaped surface positioned at the front of said detachable portion and a heating element cemented on said C-shaped surface, conducting rods connected to the ends of said heating element and extending through and protruding from said openings in said detachable element and into the aligned openings in said fixed portion, copper sleeves in the openings in said fixed portion, conductors forming contact between said copper sleeves and said lead, and means for detachably securing said fixed portion to said detachable portion, said means comprising a circumferential groove in the exposed edges of said fixed portion and said detachable portion and a strap spring nested in said groove, the ends of said spring adapted tobe manually pushed outwardly to allow detachment of said detachable portion.

4. In laboratory apparatus for heating test tubes, a ceramic body, a lead attached to said body, a heating unit comprising a fixed portion and a replaceable portion, said replaceable portion having a C-shaped front surface portion for receiving tubes, and a heating element disposed upon the glued to said front surface, cylindrical openings in said replaceable portion, conductors disposed in said openings and connecting with said heating element, said conductors protruding from the rear of said replaceable element, cylindrical openings disposed in said fixed portion aligned with the first mentioned cylindrical openings, arcuate contact surfaces in said last mentioned cylindrical openings adapted to receive and continue contcat with said protruding conductors, a pair of additional cylindrical openings disposed at right angles to the before mentioned cylindrical openings, conductors received in said openings and contacting said arcuate contact surfaces, said conductors continuing contact from said arcuate contact surfaces to said lead.

5. In laboratory apparatus a heating unit tilted at an angle to the horizontal and comprising a replaceable portion and a portion fixed to a lead, said fixed portion provided with a pair of cylindrical openings for receiving conductors from said leads, a pair of cylindrical open ings in said replaceable portion aligning with the openings in said fixed portion, a C-shaped surface positioned at the front of said detachable portion, a heating element disposed on said C-shaped surface, projections intermittently positioned on said C-shaped surface and'formed integrally therewith, conducting rods connected to the ends of said heating element and extending throughand protruding from said openings in said replaceable element and into the aligned openings in said fixed portion, arcuate contact surfaces in the openings in said fixed portion, a pair of additional cylindrical openings in said fixed portion disposed substantially at right angles to said first mentioned openings, and terminating therein at one end, conductors disposed within said last mentioned openings and making contact between said arcuate contact surfaces and said lead.

Reference Cited in the file of this patent UNITED STATES PATENTS 1,966,949 Goldstein July 17, 1934 2,031,019 Walker et al. Feb. 18, 1936 2,220,043 Humphrey et 'al. Oct. 29, 1940 2,470,353 Jordan May 17, 1949 2,532,014 Davis Nov. 28, 1950 

